Polyarteritis Nodosa - PAN

Polyarteritis nodosa (PAN) is a necrotizing vasculitis resulting in aneurysmal formation and organ infarction. It is categorized as a medium-vessel vasculitis (Chapel Hill, 2012).

Quick Answers for Clinicians

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Diagnosis

Indications for Testing

Unexplained systemic illness with multiple system involvement (renal, neurologic, dermatologic)

Laboratory Testing

Histology

  • Small- and medium-size artery necrotizing vasculitis with absence of glomerulonephritis
  • Arterioles, capillaries, and/or venules – most affected
  • Immunofluorescence fails to demonstrate complement or immunoglobulin in vessel walls

Imaging Studies

Angiography – microaneurysms and stenoses of medium vessels.

Differential Diagnosis

Background

Epidemiology

Risk Factors

Chronic hepatitis B

Clinical Presentation

  • Constitutional – fever, malaise, weight loss, arthralgias
  • Cardiovascular – acute coronary syndrome
  • Dermatological – vascular purpura, livedo reticularis, lower extremity ulcers, subcutaneous ulcers
  • Gastrointestinal – nonspecific abdominal pain, gastrointestinal bleeding, bowel perforation
  • Neurological – mononeuropathy multiplex
  • Renal – renovascular hypertension, vascular nephropathy

Pediatrics

Epidemiology

  • Age – peak is 9-11 years
  • Sex – M<F, slight

Clinical Presentation

  • Tends to be a more limited disorder than in adults
  • Constitutional – fever, malaise, weight loss
  • Musculoskeletal – arthritis/arthralgia, myositis, myalgia
  • Renal – vascular hypertension, hematuria, proteinuria
  • Neurological – peripheral neuropathy
  • Gastrointestinal – nonspecific abdominal pain
  • Dermatological – livedo reticularis, skin nodules, skin infections

Indications for Testing

Unexplained systemic illness with multiple system involvement (renal, neurologic, dermatologic)

Laboratory Testing

  • Nonspecific testing
    • CBC – anemia, leukocytosis, thrombocytoses
    • C-reactive protein (CRP) – usually elevated
    • Urinalysis (UA) – proteinuria, hematuria, red cell casts
    • Electrolytes – increases in blood urea nitrogen (BUN)/creatinine not uncommon
  • Antineutrophil cystoplastic antibodies (ANCA) – rarely positive

Differential Diagnosis

ARUP Lab Tests

Identify anemia, leukocytosis, and thrombocytoses

Screen for various metabolic and kidney disorders

Preferred test to detect acute phase inflammation (eg, autoimmune diseases, connective tissue disease, rheumatoid arthritis, infection, or sepsis)

Preferred reflex panel for managing patients with a known diagnosis of vasculitis; may be assistive in evaluating suspected vasculitis

For the workup of suspected vasculitis, the preferred panel is antineutrophil cystoplasmic antibodies (ANCA)-associated vasculitis profile (ANCA/MPO/PR3) with reflex to ANCA titer

Panel includes ANCA, IgG; myeloperoxidase antibody; and serine proteinase 3 antibody

Reflex pattern: if screen is positive, titer and MPO/PR3 antibodies testing will be added to aid in antibody determination

Can be ordered as part of the acute hepatitis panel which includes hepatitis A virus (HAV) IgM, hepatitis B virus (HBV) core antibody IgM, HBV surface antigen (HBsAg), and hepatitis C virus (HCV) antibody; refer to acute hepatitis panel with reflex to HBsAg confirmation

Reflex pattern: if results for HBsAg screen are repeatedly reactive with an index value between 1.00 and 50.00, then HBsAg confirmation will be added

Aid in initial diagnosis of connective tissue disease

Detect antibodies against double-stranded DNA (dsDNA), histones, SS-A (Ro), SS-B (La), Smith, Smith/RNP, Scl-70, Jo-1, centromere proteins, and other antigens extracted from the HEp-2 cell nucleus

Results are not disease specific

Lower sensitivity than ANA IFA for systemic autoimmune rheumatic diseases

Reflex pattern: if ANA are detected by ELISA, then ANA, HEp-2, IgG by IFA will be added

Detect glomerular basement membrane (GBM) antibodies in suspected or established anti-GBM disease

May be useful for monitoring treatment response

Positive result should be confirmed by renal biopsy

Panel includes GBM antibody, IgG by multiplex bead assay and IFA

Related Tests

Nonspecific test used to detect inflammation associated with infections, cancers, and autoimmune diseases

Detect acute or chronic hepatitis B virus (HBV) infection

Medical Experts

Contributor

Slev

Patricia R. Slev, PhD
Associate Professor of Clinical Pathology, University of Utah
Section Chief, Immunology; Medical Director, Immunology Core Laboratory, ARUP Laboratories
Contributor

References

Additional Resources
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